In situ grown Co3O4 on hydrogen storage alloys for enhanced electrochemical performance

• Co3O4 nanosheets in situ growing on hydrogen storage alloys were prepared.
• The fabrication strategy of the composites is simple, facile and effective.
• Hybrid electrodes show enhanced discharge capacity and high-rate dischargeability.
• The mechanisms behind enhanced electrochemical performance are revealed.

Co3O4 is an effective additive to enhance the electrochemical performance of hydrogen storage alloys. However, the low utilization efficiency has become a big challenge for direct adding Co3O4 powders into the alloys with mechanical mixing. Here, we report the in situ growth of Co3O4 on the alloy surface by using a facile and effective hydrothermal method. Compared with bare hydrogen storage alloys, the fabricated composite shows larger maximum discharge capacity, 326.37 vs. 302.62 mAh g−1, and enhanced high rate dischargeability with larger discharge capacity at a current density of 3000 mA g−1, 59.01 vs. 40.88 mAh g−1. These are contributed by the unique hybrid architecture of the composite: (1) the in situ grown Co3O4 nanosheets improve the catalytic activity and utilization efficiency of Co3O4 on the electrochemical reaction kinetics; and (2) the low-dimensional Co3O4 coatings seamlessly integrated with hydrogen storage alloys decrease the internal resistance and polarization of the hybrid electrode. Such a simple and novel method can also be extended to other energy storage devices.